Electrostatic measuring instrument



Patented July 26, I898.

No. 608,I32.

J. F. KELLY.

ELECTROSTATIC MEASURING INSTRUMENT.

(Application filed Apr. 14, 1898.)

(No Model) WITNESSES:

1.1% MM@WJ W ATTORNEY written YATES twice.

ATET

ELECTROSTATIC MEASURING INSTRUMENT.

SPECIFICATION forming part of Letters Patent No. 608,132, dated July 26, 189 8.

Application filed April 14, 1898. Serial No. 677,556. (No model.)

To all whom it may concern/3 Be it known that 1, JOHN F. KELLY, a citi-,

following is a full, clear, and exact descrip Men.

My invention relates to electric meters which have relatively fixed and movin g vanes and the object is to improve the construction of the same. I-Ieretofore in this class of apparatus the fixed vanes have not been protccted from each other by insulation interposed between the same, or else they have been placed upon the surface of a dielectric, and in some cases this dielectric had projections extending between the several vanes. These latter constructions were advantageous; but they did not prevent a creeping of the electric charge. This creeping of the charge is very objectionable. in this class of devices, as it considerably enlarges the effective size of such vanes, the virtual increase depending largely upon the frequency of the alternations of the current employed, growing with the decrease in frequency of the same and arriving at a maximum with direct currents. The creeping is also affected by the state of the weather, the condition of the surface of the dielectric, &c. This creeping of the charge and consequent change in the virtual dimensions of the conducting-vanes introduces irregularities into the actionof the instrument, which the present construction is designed to avoid. When the conducting-vane is embedded in the dielectric, there is practically no varying of the charge, the virtual dimensions of the conductingvane being always practically the same as its physical dimensions. Another advantage of my construction is mechanical, for the device may be assembled more easily and quickly than in the case where the vanes are merely laid upon the surface of thedielectric.

In the preferred embodiment of my invention the fixed vanes are formed of a system of magnets, which system has consequent poles, and an armature extends along the space between these poles to direct the magnctic flux which passes through the moving vane, and in this way makes said vane practically dead-beat.

In the accompanying drawings, showing the preferred embodiment of my invention, Figure 1 represents a plan view of my device, the parts beingbroken away. Fig. 2 shows a detail of thespring mechanism.

A is a base for supporting the operative parts of the device.

B, O, D, and E are fixed vanes in the form of quadrants of a cylinder and are shown by dotted lines as embedded in the surrounding dielectric substance. In this embodiment of my invention the vanes consist of permanent magnets, disposed, as shown, so that they have two consequent poles N. N and S S. A fixed armature H extends along part of the space between these consequent poles in or der to direct the magnetic flux across the space and through the moving vane.

O is a movable vane carried by a suitable bearing atK onthe arm L and another on an extension from the base M and carrying a pointer G, which extends over a graduated scale, as shown. The vane 0 preferably has T-shaped heads F F, as shown, and preferably of such a shape as to extend over the ends of the fixed armature H. Reverselycoiled springs N N are fixed at their centers to the shaft upon which is mounted the vane O in a familiar manner and serve to exert a force upon the vane contrary to that exerted upon said vane by the currentit is desired to measure. The circuit is connected to the binding-posts P and R, and connections from the same are made to the fixed vanes B D and to the fixed vanes E O and through the arm L to the vane O, as shown, for an indicatingvoltmeter. In this device either direct or alternating currents may be measured. I The action upon the vane O as a consequence of the magnetic flux passing through it has a damping effect, preferably so as to makethe vane practically dead-beat and is entirely distant from the torque exerted upon said vane as a consequence of the inductive action of the fixed vanes.

It will be evident that this construction can be greatly changed without departing from the spirit of my invention.

damping effect need be employed, or the ar- For instance, no"

mature H might be a magnet having its north pole facing the consequent south poles of the vanes and its south pole the consequent north poles,and also the fixed vanes might be simply soft-iron armatures, the bar H being a permanent magnet, or other damping means might be substituted.

Another advantage of this construction is that it does not introduce other and especially exterior conducting pieces which would distort the electric field and therefor introduce irregularities into the instrument. My construction therefore allows of a more accurate calibration, and consequently reading, of the instrument.

By using different connections which are well understood the instrument above described may be used for other purposessuch, for instance, as a ground-detector, in which case the movable Vane 0 would be grounded.

What I claim is 1. In an electrostatic meter having fixed and movable vanes, a vane electrically connected to a conductor carrying electrical energy, and embedded in a dielectric to prevent creeping of the charge.

2. In an electrostatic measuring instrument in combination, a plurality of sets of relatively-fixed vanes each vane being embedded in a separate mass of insulating dielectric, and an indicating-needle having a vane movable within the inductive influence of said fixed vanes.

3. In an electrostatic measuring instrument in combination, a system of magnetic material consisting on the one part of fixed vanes and the other of a bar partially bridging portions of said fixed vanes, one of said parts being a permanent magnet, a vane, movable under the influence of the inductive action of said fixed vanes,and cutting the magnetic flux of said permanent magnet.

4. In a static measuring instrument in combination, a system of magnetic vanes having consequent poles, and means to aid in directing the magnetic flux between said poles, the vanes of said system being adapted to be electrically connected to an electric circuit, and a vane within the inductive action of said magnetic vanes and movable within said magnetic flux, substantially as described.

5. In a static measuring instrument in combination, a system of magnetic quadrants so arranged as to have consequent poles, and adapted to be electrically connected with a source of electrical energy and substantially embedded in a dielectric to prevent creeping of the charge, and a relatively-movable vane moving within the magnetic field between said consequent poles.

Signed at Pittsfield, ltlassachusetts this 9th day of April, 1898.

JOHN F. KELLY. WVitnesses:

M. L. NICHOLS, H. M. PLATT. 

